Much of the world, from the usual suspects in Iran and Russia to legislators in the U.K., seems to believe that President Barack Obama will use the enforcement of an international norm against using chemical weapons to plunge into Syria's civil war. To think that, you have to see his policy to date as a two-year head fake.

Let's be rational for a moment -- it isn't so. Obama has been diligent in trying to keep the U.S. out of the war in Syria, at one point ignoring his collective security chiefs to do so. Intervening in Syria has, as a result, been left to Iran, Hezbollah, Saudi Arabia, Qatar, Turkey and al-Qaeda in Iraq. You can argue about whether that has been a smart or humane policy, but you cannot argue with the fact that Obama is a reluctant warrior in Syria.

The words "invade," "regime change" and even "intervention" shouldn't have a place in the debate about whether to back Obama’s response to chemical-weapons use in Syria. Intervening to end Syria's war and suffering is a worthy goal, but it can't be done with two or three days of cruise-missile strikes. Even NATO's 1999 air campaign against Serbia, which involved 38,000 aircraft sorties over 78 days, could not have succeeded if the goal had been to remove Slobodan Milosevic from power, as opposed to prompting him to clear his troops out of Kosovo. Milosevic would have fought on to the last (other) man to preserve himself. Bashar al-Assad would be no different.

Unplanned mission creep is a genuine risk, and Assad could force deeper U.S. involvement by retaliating. Yet I think that risk is being wilfully exaggerated. The Syrian leader didn't respond to previous limited air strikes by Israel, and he probably isn't dumb enough to volunteer for an escalating war with the U.S. military, either. There are plenty of lessons to learn from the Iraq war, but that it ended well for Saddam Hussein isn't one of them.

And yet the confusion over Obama's military intentions is widespread and palpable. Why?

Part of the fault lies with the U.S. president and part with his unwanted inheritance. Very little has been clear about Obama's enforcement of the red line he drew for chemical-weapons use in Syria since it was first crossed several months ago. Now his decision to ask Congress has turned an issue of principle and U.S. credibility in the Middle East into a coin toss.

Much of the doubt about Obama's proposed enforcement, though, has also been encouraged by past U.S. malfeasance. It's like crying wolf, and the key relevant instances can be ranked in the following order:

  • Iraq (the George W. Bush administration and its allies invaded Iraq saying they knew Saddam Hussein had weapons of mass destruction when he didn't);

  • Libya (the U.S. and its allies turned a United Nations Security Council resolution permitting a no-fly zone and protection of civilians into a license for regime change);

  • Halabja (the Ronald Reagan administration blocked sanctions against Saddam for using of chemical weapons against ethnic Kurds in Halabja in 1988, because at the time he was a U.S. ally against Iran.)

The cost of all this dishonesty is that few governments, and even among allies few citizens and lawmakers, trust the U.S. to dispense justice in the place of a UN Security Council so divided that it has been rendered impotent. What’s more, most Americans are only too happy to give up their country's role of global policeman. That's terrible news for Syrians and, even if we don't yet realize it, for the rest of us.

(Marc Champion is a Bloomberg View editorial board member. Follow him on Twitter.)